The invention concerns a mixing tool for bulk materials and/or similar materials for attachment to a shaft in a drum of a mixer, drier and/or reactor with a first mixing tool surface F.sub.1 acting on the bulk material during rotation of the shaft which is associated with a first tool profile surface F.sub.P1 and with a second mixing tool surface F.sub.2 radially displaced therefrom which is associated with a second mixing tool profile surface F.sub.P2, wherein the first and second mixing tool profile surfaces F.sub.P1 and F.sub.P2 extend in a radial direction from the surface of the shaft in a mutually adjacent non-separated fashion.
A mixing tool of this kind has become known in the art through DE 29 42 325 C2.
In order to process bulk materials rapidly and homogeneously it is necessary for the individual bulk material particles to be exchanged among each other in an intensive manner and as evenly as possible. With a plurality of conventional mixing tools consisting essentially of a holding arm and a mixing body, differing motional dependences can be produced in a material bed which depend essentially on the geometrical configuration of the mixing body.
The geometrical shapes of the conventional mixing bodies are generally adjusted to the kind of material processing, namely in dependence on whether or not the material is to be processed with a plough tool (push mixer), in a mechanically produced spiral bed (plough share mixer) or in a product ring (centrifugal mixer). Different types of processing result in the most differing of processing times and product qualities after processing.
A mixing tool is known in the art from DE 29 42 325 C2 which has a first mixing tool surface and a second mixing tool surface. These mixing tool surfaces directly border each other in a radial direction and extend from a mixer shaft nearly up to the inner wall of the drum. Conventional mixers strive to break-up a dried product for facilitating as intensive an exchange as possible with heated contact surfaces of the drum or with a gas stream of increased temperature flowing through the drum. The mixing surfaces of the conventional mixing tool are wedge-shaped and have surfaces which are not adapted to another. The conventional mixing tool is distinguished in that it initially extends in a rod-like fashion radially from the mixing shaft and maps, in the vicinity of the inner wall of the drum, into a rod extending parallel to the shaft.
Another mixing device is known in the art from DE-AS 1 101 113 having mixing tools with tool surfaces which are separated from another. These tool surfaces (pair-wise disposed centrifugal scoops) each move a product to be processed in opposite transport directions.
It is the underlying purpose of the present invention to further improve the conventional mixing tool in such a manner that the motion of the materials to be processed in a drum, as seen over the cross-section of the drum, is improved independent of the angular rotation of the shaft both with regard to an axially directed material exchange as well as with respect to a radial directed material exchange.